OTTAWA - As one of Hong Kong's leading democracy advocates, Martin Lee says he's not surprised when the Chinese government tries to shut him up.

"This happens to me every time I travel," the 76-year-old Lee told The Canadian Press over the phone before he boarded a plane out of Ottawa late Tuesday afternoon.

Earlier in the day, he appeared as planned before the House of Commons foreign affairs committee to offer a briefing on the embattled democracy movement in Hong Kong.

Lee's testimony occurred after the barely concealed threats of an indignant Chinese ambassador who sent a sternly worded letter to the committee telling it to rescind his invitation.

"Obviously, it didn't work. I suppose the ambassador actually thought it would," said Lee.

No "respectable committee of Parliament," Lee said, would ever bow to the will of the Chinese government to silence him.

Lee, the veteran pro-democracy activist, was one of several people arrested in December after more than two months of demonstrations against restrictions that the Beijing government is imposing on Hong Kong's first election in 2017.

The protests paralyzed Hong Kong and gave rise to a new opposition movement that is seen by Chinese President Xi Jinping as a threat to his country's stability.

So with Lee set to testify in Ottawa on Tuesday, Chinese ambassador Luo Zhaohui sent a letter to the committee and the Foreign Affairs Department that essentially told Canada to butt out of China's domestic affairs. He said it would be best not to rock the boat on Canada-China relations.

Lee said he is used to the Chinese government kicking up this sort of fuss when he speaks abroad.

Earlier this year, the members of a committee of the British House of Commons wanted to travel to Hong Kong to study the democracy movement, but Lee said the Chinese government did not grant the necessary visas.

So they held their hearings in London, and Lee testified there.

He said Canada has a "moral obligation" to speak up for democracy in Hong Kong in the face of Chinese efforts to stamp it out.

"I would put it no higher, but certainly no lower."

Johanna Quinney, spokeswoman for Foreign Affairs Minister Rob Nicholson, said Canada recently raised concerns about "the treatment of political dissidents" with senior Chinese government leadership.

"Canada continues to support the rule of law and the democratic aspirations of the Hong Kong people," she said in an email.

In the upcoming 2017 election, the Hong Kong government has caved to Beijing's desire to select all the candidates to run as its leader, which is a blatant violation of the past promise of universal suffrage, said Lee.

Prior to the British handover of Hong Kong to China in 1997, Lee said both countries courted international support for the "one country, two systems" policy that would allow Hong Kong to retain its political system.

In the last two years especially, said Lee, China has been flouting that commitment in Hong Kong.

"The communist interference is so blatant, they don't even deny it," Lee said.

Lee will eventually return to Hong Kong, but with mixed emotions.

He's happy that the student-led protests with their peaceful civil disobedience brought attention to the issue, but he's sad it was necessary in the first place.

Lee wasn't detained long after his arrest with several others this past December.